Triple whistle does exactly that, a three stage whistle effect over 25 shots. This is a great alternative to old style whistling bottle rockets and you could argue more cost effective to coming in at just under £10. I have a soft spot for these as i'm a big fan of novelty fireworks! Specifications as follows:- CAT2 / F2, 1.4G, 20mm Bore, 30 second duration.
More info:- https://epicfireworks.com/triple-whistle-25-shot
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